The present invention relates to apparatus for applying insulating sleeves to an electrical and mechanical joint between ends of electric cables and of the type in which a cylindrical tubular support around which an elastically expanded sleeve of elastomeric material is disposed, said tubular support being provided with an inner cavity having a diameter greater than the outer diameter of the cables to be joined and removing means acting on the sleeve and on the tubular support to remove this latter from the sleeve itself after said support and said sleeve have been positioned at the joining zone of the cables.
As is known, when two electric cables are joined together at their respective ends, it is necessary to apply, in the joining zone, a sleeve which has the double function of providing an adequate electrical insulation in said zones and of protecting the joining from the various outside agents, such as moisture, dust, etc.
A type of sleeve widely used in the field is substantially made of elastomeric material with such dimensions that when applied on the joint, the sleeve itself exerts a sufficient radial pressure on the outer surfaces of the insulations of the cables. This condition is necessary in order to assure the lack of air bubbles at the interface between the sleeve and the surface of the insulations of the cables, the presence of which seriously impair the capability of the sleeve under operating conditions.
During the manufacture of the sleeves, they are previously fitted, while elastically expanded, around appropriate cylindrical tubular supports of a rigid material, such as, for example, polymeric materials, which can be easily applied on the joints of the cables. During application, the tubular support, which has an inner diameter greater than the diameter of the cables, is fitted around one of the cables before the cables are joined. Following the mutual interconnection of the conductors of the cables, the tubular support together with the sleeve fitted therearound, is symmetrically arranged on the joining zone and the support is then removed from the sleeve. Therefore, the sleeve shrinks elastically around the joint and perfectly matches the surfaces of the insulations of the cables in the joining zone.
The release of the tubular support from the sleeve is effected through removing means which, at the present state of the art, is essentially constituted by a plurality of annular flanges consecutively connected by threaded rods engaging, during application, through the flanges themselves by way of respective interposed bushings. The flanges are coaxially aligned along a portion of the tubular support which projects outside the sleeve. More specifically, one of said flanges abuts on an outer shoulder provided outside the sleeve, while another flange acts on an annular projection provided on one end of the tubular support. In this way, acting on the bushings that connect each flange to the threaded rods, the flanges move away from each other and consequently the tubular support is removed from the insulating sleeve.
One of the more relevant drawbacks of the known technique consists in the risk of causing tears or cuts at the outer surfaces of the insulations of the cables during the removal of the tubular support from the sleeve. In fact, the insulations of the cables do not have a high mechanical rigidity and are subject to the risk of bending, e.g., under the effect of their own weight, during the joining operation and the application of the sleeve. Therefore, it may easily happen that when the tubular support is removed from the sleeve as previously described, the edges of the ends of the support slide with force on the outer surface of the insulations of the cables thereby damaging the insulations.
Other drawbacks arise when, after the application of the sleeve, the tubular support has to be cut longitudinally in order to remove it from the cables. The operations for cutting the support are in fact quite difficult, especially when the cables are placed in narrow spaces, and consequently, it may happen that the cables are inadvertently damaged with the cutting tools used.
Also, the flanges provided in the removing means must be cut so as to be removed from the cables. This need gives rise to complications which are to be added to those previously described and, moreover, produces an economic loss since the flanges, after the cutting operation, obviously cannot be utilized again.
The main object of the present invention is substantially that of overcoming the drawbacks of the known techniques by providing apparatus able to eliminate any possible risk that the ends of the tubular support will interfere with the outer surface of the insulations of the cables during the removal of the support itself from the sleeve and which makes the operations for obtaining the release of the removing means and the tubular support from the cables relatively simple.